Ultra-compact beam splitter and filter based on a graphene plasmon waveguide.

Area of Science:

• Photonics
• Materials Science
• Nanotechnology

Background:

• Mid-infrared (MIR) photonics requires compact and tunable optical components.
• Graphene surface plasmons (GSPs) offer unique properties for manipulating light at the nanoscale.
• Existing devices often lack the desired compactness and tunability for MIR applications.

Purpose of the Study:

• To propose and analyze a novel graphene-ribbon waveguide structure.
• To demonstrate its capability as an ultra-compact beam splitter and filter in the MIR waveband.
• To investigate the tunability of device performance through various physical parameters.

Main Methods:

• Numerical simulations using the finite-difference time-domain (FDTD) method.
• Analysis of graphene surface plasmon (GSP) wave propagation.
• Parametric study involving chemical potential, waveguide width, gap distance, substrate refractive index, and carrier relaxation time.

Main Results:

• The proposed graphene-ribbon waveguide functions as a simple and ultra-compact splitter and filter.
• Central wavelength and coupling intensity are effectively tunable by adjusting physical parameters.
• Detailed numerical depictions illustrate the impact of parameters on GSP waves and beam-splitter performance.

Conclusions:

• The graphene-ribbon waveguide is a promising platform for miniaturized MIR optical devices.
• The structure enables fast tunability for beam splitting and filtering functionalities.
• Potential applications include ultra-compact tunable beam splitters, filters, modulators, and switches in the MIR range.